Various attempts have been made heretofore to strengthen ear-like structures of clamps, especially hose clamps, in order to increase their holding ability and/or their spring properties which determine the elastic re-tightening forces in case of expansion of the hose clamp due to temperature and/or pressure increases. For example, narrow reinforcing grooves of more or less canoe shape as viewed in plan view have been proposed in my prior U.S. Pat. No. 3,475,793 for the bridging portion of so-called "Oetiker" ears. My prior U.S. Pat. No. 3,510,918 proposed the use of an elastic insert member to control the elastic properties of the ear. A plug made from rod-shaped elastic material or hollow spring steel was also proposed in my prior U.S. Pat. No. 3,579,754. Considerable improvements for increasing the holding ability of ear-like structures were attained with a reinforcing depression provided in the bridging portion of the ear-like structure, as more fully disclosed in my aforementioned copending application Ser. No. 06/922,408, the subject matter of which is incorporated herein and has been published in my corresponding British Patent 2,160,577. According to this application, the reinforcing depression is a relatively shallow, generally pan-shaped depression of generally rectangular shape as seen in plan view with the sides extending over substantial portions of the width and length of the bridging portion in its non-reinforced condition. Though the various ways of increasing the holding ability of ear-like structures and/or controlling the elasticity thereof, as proposed heretofore by me, have proved very successful, the advent of new hose materials and/or applications to ever-greater ranges of temperature and/or pressure changes demand ever-improved characteristics in hose clamps. Proposals have also been made heretofore by others to address these and other problems. For example, the U.S. Pat. No. 3,087,221 proposed a hose clamp which had its greatest radial band thickness near the middle with the thickness progressively reduced towards the ends for the avowed purpose to maintain a true circle initially and upon change of diameter. In FIG. 3 of this patent, the ear itself was also proposed to be made in the same manner as the clamping band, i.e., having its greatest thickness in the middle with reduced thickness toward the ends of the ear. Apart from a lack of disclosure of how the clamps as proposed in this patent could be realized in practice, this patent was concerned only with maintaining a true circular configuration of the parts in question.
The European Patent 0 208 598 discloses an arrangement for a clamp structure provided with an outwardly extending circular fold or loop in the clamping band in which the elasticity reserve is to be determined by a slotted sleeve surrounding the fold or loop. According to this patent, the outwardly extending fold or loop is to limit the elasticity reserve in a fold or loop of the type shown in FIG. 1 in my prior U.S. Pat. No. 3,475,793 in which bent-out lugs or folds constitute tensional spring elements.
Another approach to affecting the holding ability of a so-called "Oetiker" ear can be found in my prior Swiss Patent 580,247 in which the plastically deformed ear can be subjected only to a predetermined maximum reopening force. However, the force for reopening the ear up to its maximum limit is unaffected by this arrangement.
The more recently issued U.S. Pat. No. 4,430,775 proposed a banding strap for attaching a heat shield to a muffler in which the overlapping band portions were provided with outwardly projecting folds so constructed and arranged that the fold in the inner band is received in the bite of the fold in the outer band. The inner and outer bands are held in position by a "snap-in" feature preventing the folds from springing apart before they can be crimped together. Furthermore, lateral misalignment is intended to be prevented by dimples which also add material strength and stiffness to the central sections of the folds. However, tests have indicated that the nesting arrangement of the folds as disclosed in this patent will not, as such, materially strengthen the fold's holding ability over that in a hose clamp with a similar fold but constituted only in the outer band portion, i.e., by a single band layer.